1. Field of the Invention
The present invention relates to an LCD panel driving circuit, and more particularly to an LCD driving circuit and method for increasing effective bit(s) of source drivers thereof.
2. Description of the Prior Art
Liquid crystal displays (LCDs) have been widely used, for example, in notebook computers or television, for the advantages of low radiation, low power consumption, and light weight. As the 6-bit Digital-to-Analog converter (DAC) of the LCD that only provides 64 scales (or levels) has become unsatisfactory to users, some schemes are disclosed to increase effective bits of the DAC, among which frame rate control (FRC) is a technique, utilized to increase effective bit(s) in the DAC. In the FRC technique, for example, four frames of the original black and white scales are sequentially displayed to make out five different scales in vision effect. Among the five scales, two scales (i.e., the black and white) are the original scales, and the other three scales are generated through the FRC technique. Accordingly, the DAC used in FRC technique having 1 bit (i.e., two original scales) substantially functions as a 3-bit (i.e., 1+2 bits) DAC, in which five scales are displayable. Similarly, a DAC having 2 bits (i.e., four original scales) substantially functions as a 4-bit (i.e., 2+2 bits) DAC, in which 13 (3×3+4) scales are displayable. Likewise, a DAC having 6 bits (i.e., 64 original scales) substantially functions as an 8-bit (i.e., 6+2 bits) DAC, in which 253 (3×63+64) scales are displayable. There is need for improving or even replace the FRC technique for the reason that it does not provide complete set of scales to the DAC. For example, 253 instead of 256 full scales are provided by the 6-bit DAC with the FRC technique. Furthermore, the DAC possesses noise-like flicker on display, especially for the large-size panel.